Color printers have become exceedingly popular. Previously, such printers were mainly used only for professional purposes, since their cost could run into the thousands of dollars. Professional artists and entities concerned with printing color images and documents on various types of media had at their disposal high-end printers that could generate very life-like color prints. More recently, however, the cost of color printers, including laser printers but more usually inkjet printers, has plummeted, resulting in their purchase by home users and other non-professionals. With the advent of applications like digital photography, such low-cost color printers are increasingly being used to print color prints of photos, computer-drawn images, and other types of documents.
Regardless of the type of color printer, color calibration is an important process for color printers and other types of devices. Color calibration maintains color consistency from specific printer to specific printer, from print job to print job, from one day to the next, and so on. Calibration is especially important when maintaining critical colors, such as colors in company logos, production of multiple prints in a single print job, production of various jobs, and so on. Modern color printers can produce excellent color output, but colors tend to drift over time, causing consistency and other problems for users.
There are generally four reasons why color calibration should be performed. First, as much as a 10–20% variation can exist in the ink drop size between otherwise identical printers, and otherwise identical ink cartridges, due to manufacturing variations. Second, variation can also exist in the composition of different ink produced at different times. The third and fourth reasons are environmental factors, including temperature and humidity, which can vary at different times when the printer is used.
A color calibration module can contain a test target of a number of color patches that range from 0 to 100% ink coverage for each ink color the printer uses. The purpose of this test target is to allow users to evaluate ink coverage. After printing the calibration target, users typically read the target with a device that generates optical density or other types of values, which are entered into the calibration module to determine the adjustment necessary to provide for consistent colors. Optical density values in particular provide a numeric value that correlates to ink film thickness, where high optical density values relate to heavier ink coverage, and lower optical density values relate to lighter ink coverage. Devices that can measure such optical density and other values include densitometers, calorimeters, spectrophotometers, and other types of devices. A common type of color calibration approach is referred to as linearization, in which a straight-line relationship between color input and color output is determined.
A difficulty with existing color calibration modules is that they tend to be tied to specific measurement devices, output devices, test targets, color calibration approaches, such as linearization, and so on. However, quality and cost requirements differ based on different user's needs. For example, high-end users likely want the highest quality possible, and are willing to waste media and ink, expend the time necessary to achieve accurate color calibration, and buy specialized measuring tools, to ensure that color consistency is maintained as accurately as possible. Conversely, low-end users likely want only a given degree of color consistency, to minimize waste of media and ink, to expend a minimal amount of time for color calibration, and do not wish to buy specialized equipment. Current color calibration modules cannot accommodate this difference in needs.
Furthermore, existing color calibration modules typically are geared to only a given color calibration approach, such as only linearization. However, different users may have different requirements, and may want to use a number of different calibration approaches at different times, and so on. Different users also likely will want to generally use different calibration approaches, which existing color calibration modules cannot accommodate. For these and other reasons, therefore, there is a need for the present invention.